iscntrl
From cppreference.com
Defined in header <ctype.h>
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int iscntrl( int ch ); |
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Checks if the given character is a control character, i.e. codes 0x00-0x1F
and 0x7F
.
The behavior is undefined if the value of ch
is not representable as unsigned char and is not equal to EOF.
Parameters
ch | - | character to classify |
Return value
Non-zero value if the character is a control character, zero otherwise.
Example
Run this code
#include <stdio.h> #include <ctype.h> #include <locale.h> int main(void) { unsigned char c = '\x94'; // the control code CCH in ISO-8859-1 printf("In the default C locale, \\x94 is %sa control character\n", iscntrl(c) ? "" : "not " ); setlocale(LC_ALL, "en_GB.iso88591"); printf("In ISO-8859-1 locale, \\x94 is %sa control character\n", iscntrl(c) ? "" : "not " ); }
Output:
In the default C locale, \x94 is not a control character In ISO-8859-1 locale, \x94 is a control character
References
- C11 standard (ISO/IEC 9899:2011):
- 7.4.1.4 The iscntrl function (p: 201)
- C99 standard (ISO/IEC 9899:1999):
- 7.4.1.4 The iscntrl function (p: 182)
- C89/C90 standard (ISO/IEC 9899:1990):
- 4.3.1.3 The iscntrl function
See also
(C95) |
checks if a wide character is a control character (function) |
C++ documentation for iscntrl
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ASCII values (hex) |
characters |
iscntrl |
||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0 - 8 | 0x00-0x08
|
control codes (NUL , etc.)
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
9 | 0x09
|
tab (\t )
|
≠0
|
0
|
≠0
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
10 - 13 | 0x0A-0x0D
|
whitespaces (\n ,\v ,\f ,\r )
|
≠0
|
0
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
14 - 31 | 0x0E-0x1F
|
control codes | ≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
32 | 0x20
|
space | 0
|
≠0
|
≠0
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
33 - 47 | 0x21-0x2F
|
!"#$%&'()*+,-./
|
0
|
≠0
|
0
|
0
|
≠0
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
48 - 57 | 0x30-0x39
|
0123456789
|
0
|
≠0
|
0
|
0
|
≠0
|
0
|
≠0
|
0
|
0
|
0
|
≠0
|
≠0
|
58 - 64 | 0x3a-0x40
|
:;<=>?@
|
0
|
≠0
|
0
|
0
|
≠0
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
65 - 70 | 0x41-0x46
|
ABCDEF
|
0
|
≠0
|
0
|
0
|
≠0
|
0
|
≠0
|
≠0
|
≠0
|
0
|
0
|
≠0
|
71 - 90 | 0x47-0x5A
|
GHIJKLMNOPQRSTUVWXYZ
|
0
|
≠0
|
0
|
0
|
≠0
|
0
|
≠0
|
≠0
|
≠0
|
0
|
0
|
0
|
91 - 96 | 0x5B-0x60
|
[\]^_`
|
0
|
≠0
|
0
|
0
|
≠0
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
97 -102 | 0x61-0x66
|
abcdef
|
0
|
≠0
|
0
|
0
|
≠0
|
0
|
≠0
|
≠0
|
0
|
≠0
|
0
|
≠0
|
103-122 | 0x67-0x7A
|
ghijklmnopqrstuvwxyz
|
0
|
≠0
|
0
|
0
|
≠0
|
0
|
≠0
|
≠0
|
0
|
≠0
|
0
|
0
|
123-126 | 0x7B-0x7E
|
{|}~
|
0
|
≠0
|
0
|
0
|
≠0
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
127 | 0x7F
|
backspace character (DEL )
|
≠0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|